JP4264362B2 - Insulating coating agent for grain-oriented electrical steel sheet not containing chromium and grain-oriented electrical steel sheet having an insulating film not containing chromium - Google Patents

Description

  The present invention relates to an insulating film forming technique for grain-oriented electrical steel sheets, and in particular, provides a treatment liquid that does not contain chromium, and uses it, such as annealing resistance, film tension, insulation, adhesion, and corrosion resistance. The present invention relates to a product having excellent insulating film characteristics and an insulating film forming method.

  For a grain-oriented electrical steel sheet, a silicon steel slab containing, for example, 2 to 4% of Si is hot-rolled and annealed, and then subjected to cold rolling twice or more sandwiching intermediate annealing to obtain a final sheet thickness, and then removing the steel sheet. After carbon annealing, an annealing separator containing MgO as the main component is applied, finish annealing is performed to develop secondary recrystallization with goth orientation, and impurities such as S and N are removed and a glass film is formed. Then, an insulating film agent is applied and subjected to baking and heat flattening to obtain a final product.

  The grain-oriented electrical steel sheet obtained in this manner is mainly used as an iron core material for electrical equipment, transformers, etc., and is required to have a high magnetic flux density and excellent iron loss. When a directional electromagnetic steel sheet is used as a transformer iron core, the directional electromagnetic steel sheet coil is slit, cut to a predetermined length while being continuously unwound, and stacked or wound by an iron core processing machine to be a stacked iron core or winding. It is said to be an iron core. In the case of a wound iron core, it is made into a transformer by performing a winding operation called racing after compression molding and strain relief annealing. In this transformer manufacturing process, it is important that cutting, winding, and molding can be easily performed. In particular, in the manufacture of wound cores, the adhesion of the insulating film is excellent during cutting and winding molding, and it does not impair the working environment such as powdering, and it has excellent winding workability and annealing resistance, and has coating performance, magnetic properties and workability. It is important not to damage.

  The surface film of the grain-oriented electrical steel sheet is usually composed of a forsterite film, usually called a glass film, formed during the final finish annealing, and an insulating film processed thereon. As a technique for forming this insulating film, Patent Document 1 invented, disclosed and industrialized a tension film made of colloidal silica, a phosphate, and a chromium compound by the present inventors. Further, as disclosed in Patent Document 2, a treatment agent comprising fine colloidal silica having a particle diameter of 8 nm or less and a chromium compound is disclosed in primary phosphate. Further, in Patent Document 3, by mixing colloidal silica having a particle size of 20 nm or less and colloidal silica having a particle size of 80 to 2000 nm with a primary phosphate of Al, Mg, Ca, Zn and a chromium compound, the surface of the insulating film is uniform. Techniques have been shown for obtaining a good protrusion effect and improving winding workability (sliding property), annealing resistance, and film tension in the wound iron core machining process. As a result, a tensile effect and an effect of improving iron core workability are obtained, and a grain-oriented electrical steel sheet having excellent magnetic properties and magnetostrictive properties can be obtained.

  These insulating films have been added and mixed with a chromium compound in consideration of the hygroscopicity after the film baking treatment with phosphate, the film seizure property during strain relief annealing, and the like.

The role of the chromium compound in the insulating film is the effect of filling the porous coating structure in the phosphate or phosphate and colloidal silica-based coating, and the hygroscopic decomposable free phosphoric acid remaining in the coating components after baking the insulating coating. Combined with the effect of fixing and forming a stable phosphate-chromium compound, the effect of improving the stickiness of the coating, the seizure during annealing, the coating tension and the like is brought about. When the treatment liquid contains hexavalent chromium using chromic anhydride, chromate or dichromate, there are problems in the working environment during the coating work and the waste liquid treatment work. Furthermore, in the coating after the baking treatment, Cr is almost reduced to trivalent chromium and has little harmfulness. If powdering occurs in the iron core processing step, the working environment may be contaminated. As a countermeasure, an insulating film agent not containing a chromium compound has been studied. In Patent Document 4, colloidal silica is composed of 20 parts by mass of SiO ₂ , 10 to 120 parts by mass of Al phosphate, 2 to 10 parts by mass of boric acid, and Mg, Al, Fe, Co, Ni and Zn sulfates. An insulating film forming method is proposed in which a treatment liquid containing 4 to 40 parts by mass in total of any one or two selected from among these is baked at 300 ° C. or higher.

Patent Document _{^{5, M 2+ 1-x M}} 3+ x (OH) - 2 + x-ny A ny · mH 2 O Formula average particle size 1μm or less of the solid solution type composite represented by the A treatment agent having a hydroxide composition is disclosed. In Patent Document 6, as an organic acid salt selected from Ca, Mn, Fe, Mg, Zn, Co, Ni, Cu, B and Al, formate, acetate, oxalate, tartrate, lactate, citric acid, A surface treatment agent for grain-oriented electrical steel sheets characterized by adding one or more organic acid salts selected from acid salts, succinates and salicylates has been proposed.

  These are all technologies that can exert the effect of the film tension, and are effective as they are. However, in the case of Patent Document 4, there are problems such as discoloration, insulation, and corrosion resistance during annealing with sulfate ions of the added sulfate. Further, Patent Document 6 may have a problem of color tone due to an organic substance for dissolving a metal element and a problem of solution stability. Thus, compared with the conventional chromium-containing insulating film agent, it cannot be said that the film performance has been improved sufficiently comprehensively, and further improvement has been desired.

Japanese Patent Publication No.53-28375 Japanese Patent Laid-Open No. 61-41778 JP-A-3-39484 Japanese Patent Publication No.57-9631 JP-A-7-180064 JP 2000-178760 A

  The present invention solves environmental problems by having an insulating film agent composition that does not contain a chromium compound, and provides chromium in insulation based on phosphate, such as conventional phosphate or phosphate-colloidal silica-based coatings. There are provided a grain-oriented electrical steel sheet and an insulating film agent having an insulating film with excellent film performance that solves problems of moisture absorption resistance, annealing resistance, denseness, and film tension failure when no compound is contained.

The gist of the present invention is the following structure as a grain- oriented electrical steel sheet having an insulating film agent for grain- oriented electrical steel sheets not containing a chromium compound and an insulation film containing no chromium compound .
( 1 ) One or two kinds selected from inorganic compounds of Fe and Ni with respect to 1 mol in total of one kind or two or more kinds of primary phosphates selected from Al, Mg and Ca It contains 0.06 to 2.10 mol as an element, and further contains 35 to 100 parts by mass of colloidal silica as solid content with respect to 100 parts by mass of the first phosphate, and the inorganic compound of Fe and Ni is water. An oxide, the hydroxide of Fe, Ni is a colloidal material that is stable as an aqueous solution, and the form of the colloidal material is a single compound colloid, a composite colloid with SiO ₂ or Al ₂ O ₃ , or these An insulating coating agent for grain-oriented electrical steel sheets, which is a mixture and does not contain chromium, wherein the colloidal substance has a particle size of 50 nm or less.
(2) an insulating coating, oriented electrical steel sheet having an insulating film not containing chromium characterized by der Rukoto those formed by processing baking an insulating coating agent according to (1).

According to the present invention, phosphate - in tension coating containing no chromium compound based on colloidal silica, Fe, by adding a hydroxide of N i, improves the corrosion resistance of the baking after coating, straightening A significant improvement in seizure resistance during annealing can be obtained. In particular, an extremely excellent effect is exhibited in the addition of an ultrafine colloidal substance of Fe.

The inventors of the present invention have made efforts to make a chromium-free composition in a conventional tension-imparting insulating film mainly composed of phosphate alone, phosphate, colloidal silica, and a chromium compound. That is, moisture absorption (stickiness and rust generation) after film baking treatment and seizure resistance in strain relief annealing, which were the disadvantages of the conventional composition, chromium-free phosphate, phosphate and colloidal silica main component composition And developed a coating composition to improve coating tension reduction due to coating porosity. As a result, in the tension-imparting film component mainly composed of phosphate and phosphate and colloidal silica, an inorganic compound of Fe and Ni is used as each metal element in an amount of 0.06 to 2 with respect to 1 mol of phosphate phosphate. .Insulating film with excellent corrosion resistance, annealing resistance, adhesion, slipperiness, insulation, etc., and excellent magnetic and magnetostrictive properties by adding 10 mol% to solve conventional problems of chromium-free The agent and its treatment method were successfully completed. Details will be described below.

  In application of the agent of the present invention, as a starting material, a final-finish annealed grain-oriented electrical steel sheet is used, the excess annealing separator is removed in a continuous processing baking line, and after light pickling, the insulating coating liquid is applied to the steel sheet surface. Then, a baking process is performed.

In the present invention, first, the film composition is characterized. Here, a method for forming an insulating film mainly composed of phosphate and colloidal silica will be described. That is, in the main component coating of phosphate and colloidal silica, generally from 100 parts by mass of the primary phosphate of Al, Mg, Ca and 35 to 100 parts by mass of colloidal silica in terms of solid content in order to express the film tension. A base solution is employed. As the primary phosphate, primary phosphates of Al, Mg, and Ca are used. In the present invention, with respect to the first phosphate salt 1 mole, Fe, relative to the phosphate inorganic compounds N i, is added in the range of 0.06 to 2.10 mol.

Fe with this important role, as the N i of compound, the addition of hydroxide thereof. These substances are fine particle dispersions, which are prepared and added as a siloxane-structured solution such as colloidal silica, and have effects such as solution stability, stabilization of the compound phosphate, and film filling action. A better effect can be obtained by increasing the value. Furthermore, as a more preferable condition, an aqueous dispersion of a colloidal substance having a particle diameter of 500 nm or less is used. Such colloidal materials, and simple colloidal substances hydroxide product may be either a method such as adding the composite colloidal material with SiO _2, Al 2 O _3.

The treatment agent thus adjusted is subjected to a baking process at 350 ° C. or higher after coating by controlling the coating amount using a coating roll or the like in a continuous line. The coating amount is determined depending on the thickness of the applied steel sheet and the intended use of the product. In the case of the coating agent of the present invention, a grain-oriented electrical steel sheet having excellent magnetic properties and magnetostrictive properties as well as coating performance and appearance can be obtained at ² to 10 g / m ² .

  In applying the agent of the present invention, in addition to the material in which the glass film is formed by finish annealing, the glass film is removed by pickling with a steel plate that has been prevented from forming glass by using a glass film formation inhibitor as an annealing separator, or so-called glass. It may be applied to loess materials.

When the base liquid is mainly composed of phosphate alone components also, Fe of the present invention in accordance with the phosphate, the compound of N i is added in the same manner.

  Next, the reason for limitation of the present invention will be described.

  The insulating film of the present invention is first characterized by the component of the insulating film of the product.

  First, the present invention is applied to any case where the main component is composed only of a phosphate, and when the main component is a phosphate and colloidal silica. In particular, when the latter phosphate and colloidal silica are the main components, in the chromeless composition, the structure of the coating after baking is porous, the hygroscopicity and seizure during annealing are increased, and the decrease in coating tension is reduced. As a result, an extremely large improvement effect is brought about.

An insulating film of grain-oriented electrical steel sheet products, with respect to phosphate 1 mol, Fe, 1 or two or more as each metal element you containing 0.06 to 2.10 molar insulation film agent of the Ni compound It is characterized by being formed using . The present inventors have conducted extensive research and experiments on compounds that exhibit a Cr-substituting action, and as a result, the Fe and Ni compounds are effective in filling the porous structure of phosphate, and the free phosphoric acid content. It was found that the Fe compound exhibits a very excellent effect, in particular, by bringing about a phosphoric acid stabilizing effect.

To phosphate, Fe, N i of Gobutsu as respective metal elements is less than 0.06, porous structure filled and the phosphate in the coating, the effect of suppressing the baked with resistance during moisture absorption and annealing sufficient Not. When the content exceeds 2.10 mol%, these improving effects reach saturation and are not further improved, and are limited because a slight decrease in film tension occurs.

F e, as the Ni compound are added as a hydroxide. When added by a hydroxide, it provides a filling action in the insulating film baking treatment process without impairing the film performance, and provides a free phosphoric acid fixing effect during baking or in a strain relief annealing process. From the experimental results, it was found that the most excellent results were obtained with hydroxides. This is presumed to be because the hydroxide is easily decomposed during the baking and strain relief annealing, filled in the coating, and reacted with the free phosphoric acid component to stabilize it.

Next, Fe, as the aqueous solution of the hydroxide of N i, when the colloidal dull material, excellent improvement effect is obtained. In the case of colloidal solution, a solution having a siloxane structure in the case of colloidal silica is obtained, and a solution having excellent dispersibility and stability is obtained with fine particles. When these colloidal substances are blended into the base solution, a very uniform dispersion is produced, and therefore, an extremely excellent effect is exhibited with respect to the filling action and the stabilizing action of free phosphoric acid during the baking process.

As the colloidal material, there is a method of adding each of the above-mentioned individual colloidal materials as a solution or a composite colloidal material solution in which only the surface layer part of SiO ₂ or Al ₂ O ₃ is coated. Is obtained. As the colloidal material of the present invention, the most remarkable effect was in the case of hydroxide, and in particular, the colloid of Fe hydroxide.

As colloidal materials, when the particle diameter is 500 nm or less, excellent effects of film filling and stabilization of free phosphoric acid are obtained. In particular, when the particle size is 50 nm or less, a crystalline compound prepared by a normal wet reaction is used. compared, improvement with excellent rating stage is obtained.

The application baking condition of the insulating film agent is not particularly limited, but baking is performed at a temperature of 350 ° C. or higher when baking is performed using a coating roll or the like. This is less than the baking temperature of 350 ° C., it is added to the first phosphoric acid salt, for Fe, reaction with hydroxide of N i does not proceed sufficiently, due to the reduction of such stickiness occurs. A temperature range of 350 to 450 ° C. is preferred when the product is subjected to magnetic domain subdivision treatment such as laser to obtain an effect of improving magnetic properties. However, in order to obtain a sufficient tension effect, corrosion resistance, and annealing resistance by using the thermal expansion difference at the time of baking processing as in a normal grain-oriented electrical steel sheet, baking processing at 750 ° C. to 900 ° C. is necessary. is there.

The reason for preventing the hygroscopicity after baking treatment and the seizure property of the steel sheet during strain relief annealing in the present invention is not clear, but is estimated as follows. Fe are uniformly dispersed in the solution, hydroxide of N i is decomposed in the baking process, is filled into the defect portion of the porous focal which occurs when only phosphate or phosphate and colloidal silica component. In addition, it is considered that by refining a strong and stable phosphoric acid compound, it is possible to provide a dense film, prevent hygroscopicity, and improve the film tension. In particular, it is considered that the colloidal shape of ultrafine particles has a large improvement effect due to the increase and uniformization of the reaction sites.

A sample was cut out from a high magnetic flux density directional magnetic steel sheet coil having a thickness of 0.23 mm having a glass coating on the surface of the steel sheet subjected to final finish annealing, and subjected to 850 ° C. × 4 Hr strain relief annealing after washing with water. Thereafter 2%, 85 ° C. in H ₂ SO ₄ aqueous solution, after the light pickling for 15 seconds, Fe as shown in Table 1, the treatment agent added by changing the addition conditions of the N i of compound Then, it was applied using a coating roll so that the mass after drying and baking was 5 g / m ^2, and a baking treatment at 850 ° C. for 30 seconds was performed. Thereafter, a sample was cut out from the product plate, and the film characteristics were investigated. The results are shown in Table 2.

The results of this study, Fe of the present invention, when the N i of compound added, as compared with the case without the addition of additives, hygroscopic baking after coating an anneal resistance are significantly improved, conventional chromium compound Film characteristics comparable to those of Comparative Example 3 containing No. 3 were obtained. In particular, when the Fe compound was added, a more excellent improvement effect was obtained. However, when the amount of iron hydroxide added is small, the effect is weak, and when it is too much, the result is inferior in film properties, which are inferior in liquid stability, corrosion resistance, film tension, etc. It was.

A sample was cut out from the 0.23 mm-thick high magnetic flux density grain-oriented electrical steel sheet coil that was subjected to final finish annealing in the same manner as in Example 1, and after rinsing with water, 850 ° C. × 4 Hr strain relief annealing was performed. After that, light pickling at 75 ° C. for 15 seconds was performed in a 2% H ₂ SO ₄ aqueous solution. As shown in Table 3, this steel sheet is treated with an additive containing a solution in which the particle diameter conditions of the Fe and Ni hydroxide colloidal solution are changed. It apply | coated so that it might become 5.0 g / m < ² >, and the baking process for 850 degreeC x 30 second was performed. Thereafter, a sample was cut out from the product plate, and the film characteristics were investigated. The results are shown in Table 4.

As a result of this test, when the organic acid salt of the comparative example was not added as in Example 1, the corrosion resistance and the annealing resistance were very poor. In addition, when a colloid having a large colloidal substance particle size was added as in the present inventions 6, 9 and 10, although an improvement effect was observed, the effect was not so great. In addition, when a colloidal material prepared by adding ferric hydroxide as a composite material to the SiO2 surface was added as the colloidal material, almost the same result as that obtained when the single colloidal material was added was obtained. On the other hand, an extremely large improvement effect of corrosion resistance and annealing resistance obtained by adding a compound prepared by preparing the Fe, Ni hydroxide of the present invention as a colloidal solution is obtained, compared with the case of containing a conventional chromium compound. As a result, better film performance and magnetic properties were obtained.

  Addition of colloidal ferric hydroxide (10 nm) solution to 100 ml of primary aluminum phosphate as base solution; 25 ml + primary Mg phosphate; 25 ml + 20% colloidal silica (7 nm) in the same experimental procedure as in Example 2 FIG. 2 shows the results of measuring the baking force (peeling force) when the amount is changed from 0 to 2.5 in terms of the molar ratio with the phosphate. By adding 0.06 mol or more of ferric hydroxide per mol of phosphate, the peeling force could be greatly reduced.

(A), (b), (c) is a figure which shows the method of evaluating the sticking property of the film in distortion removal annealing, and its order. It is a figure which shows the result of having evaluated the seizure property in distortion removal annealing at the time of adding and mix | blending colloidal ferric hydroxide (particle diameter 10nm).

Claims (2)

One or two kinds selected from inorganic compounds of Fe and Ni are used as metal elements with respect to 1 mol in total of one or more kinds of primary phosphates selected from Al, Mg, and Ca. 0.06 to 2.10 mol, and to 100 parts by mass of the first phosphate, further containing 35 to 100 parts by mass of colloidal silica corresponding to the solid content, and the inorganic compound of Fe and Ni is a hydroxide. The hydroxide of Fe and Ni is a colloidal material that is stable as an aqueous solution, and the form of the colloidal material is a single compound colloid, a composite colloid with SiO ₂ or Al ₂ O ₃ , or a mixture thereof. An insulating film agent for grain-oriented electrical steel sheets not containing chromium, wherein the colloidal substance has a particle size of 50 nm or less. Insulating coating, oriented electrical steel sheet having an insulating film not containing chromium characterized by der Rukoto those formed by baking the insulating coating agent according to claim 1.

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